Active galactic nuclei (AGNs) are identified using the BPT
diagram [1]} from the tG sample.
In particular, we use the demarcation line proposed by [2]},
in the \(\rm [OIII]\lambda 5007/H\beta \)  versus \(\rm [NII]\lambda 6583/H\alpha \) 
diagram. The fluxes of the four emission lines are taken from the
MPA/JHU catalog. Following [3]}, we require the four
spectral lines to have a signal-to-noise ratio greater than 3.0.
These selection criteria result in a total of 57,252 AGNs
(hereafter tAGN sample). Among them, 46,198 are central galaxies,
and the corresponding sample is denoted by cAGN.
